Compactor interlock control

ABSTRACT

A compacting machine has a reversible motor drive for a ram movable in a compacting stroke and a retracting stroke. Directional controls prepare the drive for a compacting stroke when the ram is at its fully retracted starting position and prepare the drive for a retracting stroke as soon as the ram leaves the starting position. A safety switch prevents operation of the ram unless the door is closed and the receptacle in compacting position. This switch is by-passed once the ram enters the receptacle to avoid unnecessary stopping of the compacting cycle. When the ram encounters a predetermined resistance it automatically reverses.

United States Patent [1 1 Engebretsen et al;

[ 51 Apr. 30, 1974 COMPACT OR INTERLOCK CONTROL Inventors: Einar O.Engebretsen; Victor F. Schuerman, both of Troy, Ohio Assignee: TheHobart Manufacturing Company, Troy, Ohio Filed: Aug. 11, 1972 Appl. No.:279,985

us. c|.....- 307/112, 100/52 Int. Cl. 1330b 15/14 Field of Search100/52, 50, 53; 307/117, 307/112, 149, 119, 120, 92; 318/207 C, 207 R,207 A Raeam Cited UNITED STATES PATENTS Bottas 100/52 PrimaryExaminer-Herman J. Hohauser Attorney, Agent, or Firm-Biebe1, French &Bugg [57] ABSTRACT A compacting machine has a reversible motor drive 7fora ram movable in a compacting stroke and a retracting stroke.Directional controls prepare the drive for a compacting stroke when theram is at its fully retracted starting position and prepare the drivefor a retracting stroke as soon as the ram leaves the starting j.position. A safety switch prevents operation of the ram unless the dooris closed and the receptacle in compacting position. This switch isby-passed once the ram enters the receptacle to avoid unnecessarystopping of the compacting cycle. When the ram encounters apredetermined resistance it automatically reverses.

3 Claims, 4 Drawing Figures DlRECTION SWITCH 8O PATENTEDAPR 30 IQYL FIG-1 RETRACTED 5O POSITION OF LATCH 4 5 6 m m D F E Tm T Al Rm UP R 2 5 M,m; I w w M 2 D 4 F 6 O 3 N m h m DIRECTION SWITCH I 1 I COMPACIORINTERLOCK CONTROL CROss REFERENCE TO RELATED APPLICATIONS Thisapplication is related to copending U. S. application Ser. No. 224,897,filed Feb. 9, 1972, entitled COMPACT OR, and U. S. application Ser. No.279,984, filed concurrently herewith, entitled COM- PACTOR CYCLECONTROL, both assigned to the assignee of this application.

BACKGROUND OF THE INVENTION This invention relates to trash compactingmachines and the like, and particularly to the controls for a reversibleelectric motor driving a compactingram in such a machine. The trashreceiving receptacle is connected to the access door such that the dooris closed whenever the receptacle is in compacting position. Suchmachines have safety interlock controls which prevent movement of theram from its retracted position unless the receptacle is properlylocated under the ram with the door closed. In actual use, relativelyslight movement of the receptacleand/or door has caused the interlock tostop the motor. This may be caused, for example, by force components dueto the compacting of trash items at one side of the receptacle. Due toordinary manufacturing tolerances and/or wear, only a slight suchmovement may open the interlock and stop the machine. However, if theoperator cannot then push the door in sufficiently to close theinterlock, he must call for service to free the machine.

Attempts have been made to rectify this problem, as by adding afurther'interlock switch which allows some additional movement-of thedoor and receptacle once the compacting cycle is under way. Such anarrangement is disclosed in U. S. Pat. No. 3,613,560. However, a simplersolution to the situation is desirable.

SUMMARY OF THE INVENTION A control for a reversible electric motordriving the ram of a compactor, includes a starting circuit with amanually operable starting switch which is closed only long enough toenergize a holding circuit which continues power supply to the motor. Adirectional switch is responsive to ram location at its retracted limit,also the cycle starting position, and is moved to cause forward(compacting) motor operation only when the ram is at this position. Whenthe ram leaves its starting position the directional switch transfers toreverse or retracting connections preparatory to any slowing of themotor to a speed where its centrifugal starting switch will again close.

A cycle ending switch is arranged to respond to ram movement only in theretracting direction and as the ram approaches its starting position, atwhich time this switch is actuated momentarily. The cycle ending switchis wired to open the holding circuit when it is momentarily actuated,hence power to the motor is terminated as the ram approaches thestarting position at the end of the.retracting stroke. The ram and motorcoast to a stop, by which time the startingposition is reached and thedirectional switch is moved to the forward starting position, and thecycle ending switch is again closed.

A safety door interlock switch and a key switch are provided to assurethe machine can be operated only 7 receptacle and until the'ram haspartially entered the receptacle, for example to a depth of about 1inch. Since the ram exterior is generally configured to the interior ofthe receptacle, once the ram has entered the receptacle it prevents thedoor from being opened. Any slight movement of the receptacle and door,even enough to open the door interlock switch, will not affectcompletion of the compacting cycle.

The principal object of the invention is thus to provide such acompacting machine with a control of the above described type, in whicha compacting cycle can be initiated only when the. safety interlock isclosed, but can proceed through a cycle once the ram has entered thereceptacle and the door cannot be opened, even though the receptacle anddoor may move slightly and possibly open the interlock; and in which,following stopping of the ram in its compacting stroke for any reason,subsequent ram movement will automatically be in the reverse directionto thestarting position.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view ofthe compactor showing the receptacle thereof in both its compacting andnon compacting positions;

FIG. 2 is an enlarged view of a portion of the rear of the compactorwith some parts broken away to shorten the view;

FIG. 3 is a representation of a wiring diagram of the present invention;and

FIG. 4 illustrates the manner in which the direction switch and cycleending switch are operated in relation to ram movement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS in FIG. 1.

A ram 16 is also positioned in the housing and carries a motor 18 which,through a suitable drive chain, drives sprockets 20 to cause the entireram mounted assembly to move upwardly and downwardly along thestationary jack screws-22. Preferably, three such jack screws will beutilized, arranged in triangular relationship with two jack screwspositioned adjacent the front of the housing and one jack screwpositioned centrally adjacent a rear wall of the housing.

starting and reversing control (FIG. 3) which will automaticallyinitiate a compacting stroke of the ram, and

will cause the ram to retract to its inactive position after somepredetermined load is imposed on the motor as it drives the ram in thecompacting stroke.

Mounted on a rear surface of the drawer 14, as seen in FIG. 2, is anangle shaped strike member 28 having a slot 30 formed through itsrearwardly projecting bottom leg 34. An inverted U-shaped bracket 36 isattached to the housing adjacent the rear thereof and carries asubstantially T-shaped latch member 40 rotatably mounted on a bolt 42extending through the bracket. The latch member has a downwardlyprojecting stem 44 receivable in the slot 30. A spring 45 acts betweenbracket 36'and latch member 40. A portion of the base 15 is alsoprovided with a slot 48 which aligns with the slot 30 when thereceptacle 14 is in the compacting position.

As seen in FIG. 2, the ram 16 is provided with an L- shaped bracket 50projecting to one side thereof and connecting rod 52 has its lower,forwardly bent end 53 rotatably received in an opening formed in latch40. The connecting rod is loosely received in an opening formed throughthe bracket 50 and has its upper end bent at an angle to form a stopmember 54. By properly proportioning the length of the connecting rod52, the latch member 40 will be pulled upward about its pivot such thatit clearsthe slot 30 in member 28 when the ram 16 is in its retracted orwithdrawn position as shown in FIG. 1. However, a small initial movementof the ram 16 toward the receptacle will permit the latch to be urged byspring 45 into slots 30 and 48, locking the receptacle 14 in thecompacting position within the housing. 8

While the receptacle 14 is locked in position during compacting initialmovement of the ram, access may still-be had to the interior of thecompactor through the upper access door 55. Waste material, particularlysmall items such as milk cartons, bottles, cans, etc., can be depositedin the compactor, where they will rest in a small compartment-formed bythe inclined shelf 57 and the protective wall 58, until such time as thereceptacle l4 is moved outwardly of the housing. This will allowarticles lying on shelf 57 to fall into the receptacle 14. The user,therefore, need not wait until the receptacle is unlocked to depositmaterial in the compactor, but he is of course protected against injury,etc., during operation of the ram by the wall 58.

A safety interlock switch-60, the'housing for which is shown at 61, ismounted inside the front of the housing, as seen in FIG. 1, and isengaged by a pin 62 when the receptacle 14 is in its compactingposition.

A further interlock is provided by the normally closed switch 65 whichis wired in parallel with switch 60. Switch 65 is operated by a bracket66 (FIG. 4) carried by ram 16, and arranged such that the switch isopened when the ram lower surface 24 is just below or within the upperedge 26 of the receptacle, for example within about one'inch of the edge26. In other words,

switch 65-is closed only when the ram has entered the receptacle andthus acts to prevent the drawer unit from being opened, intentionally oraccidentally.

' Thus,once the ram is inside the receptacle, which is attached to thedoor and drawer unit, the door 13 cannot be opened by the operator.However any motion of the receptacle and drawer unit, as might occurfrom off-center froces during compacting, to open the switch 60, willnot stop the compactingcycle. This minimizes the need to hold closemanufacturing tolerances on the actuator for switch 60, yet keeps themachine fully protected. It also minimizes nuisance-.typeservice callsfrom persons unable to withdraw the ram when ithas forced the doorinterlocks open and the person cannot push the drawer unit closed enoughto start it again.

Referring to FIG. 3, the control system is shown. Interlock switch 60 isclosed when drawer .14 is closed, and it controls all power to the unittogether with key switch 70. Contacts are shown in the position with thedrawer open, the ram up, motor stopped, and the key safety switch open.With the key switch 70 operated to close, and the drawer closed, pushingthe start button on starting relay 76 will close'its contact 77 andenergize its coil 78 to seal'in the relay. This also applies power tothe starting winding 80 of ram motor 18,

through the motors centrifugal starting switch 81, and.

through the contacts of a directional switch 84. The power circuit iscompleted to main winding through the overload protector 86. I

The holding circuit for relay 76 includes its coil 78, manual stopswitch 88 which is normally closed, a normally closed ram operatedswitch90, and the overload protector 86. Switch 90 is arranged to be openedmomentarily by the ram only when it is nearing'the top of its returnstroke. Its operating lever 92 has an outwardly extending arm 93 pivotedthereon, normally held by a spring 94 in the extended position as shown.

A roller 95 on the arm is in position to engage an arm 97 extending fromthe ram 16. On the downward stroke switch 90 is unaffected and remainsclosed, but on the upwardly retracting stroke the switch is momentarilyopened just as the ram approaches its fully retracted position.Directional switch 84 is carried by the ram and is held in the positionshown only when the ram is fully up. When the ram'is in any otherposition, the blades of switch 84 transfer to the contacts shown open. 1Y I i Thus, as power is first applied the motor 18 starts in a directionto lower the ram in a compactingstroke. The motor immediately comes upto speed, since it is under a slight load, and switch 81 opens andtransferring of thecontacts of switch 84 has no effect on motor motorcoasts to a stop past the actuation positon of switch 90, so that itagain closes. Switch 84 is moved to the positon shown, such that thecircuit is ready for I the next compacting stroke, just before switch 90is actuated. I I

After a compacting stroke begins switch 65 closes, bypassinginterlock'switch 60 since the ram is now inside the receptacle and latch40 is engaged. Thereafter,

if stop switch 90, or key switch 70, is opened, or the motor overloadprotector 86 opens, the circuit energizing relay 76 will be broken, andthe motor will stop. Subsequent operation of the start button 75 willenergize the motor to drive the ram upward, provided the appropriateswitch contacts are then closed.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

l. A control for a compacting machine having'a receptacle for trashmaterial and a door connected to said receptacle such that said door isclosed when said receptacle is in a compacting position, a ram mountedfor compacting movement in a compacting stroke entering said receptacleand an opposite retracting stroke to a retracted starting position, apower supply, a reversible motor connected to drive said ram, adirectional switch connected to control the forward and reverseoperation of said motor corresponding to the compacting and retractingstrokes of said ram, means normally holding said directional switch inits reverse position, a starting switch connected betweenvsaiddirectional switch and said power supply, and an interlock operable inresponse to opening of said door to disconnect said motor from saidpower supply;

the improvement comprising means for bypassing said interlock once saidram has entered said receptacle in a compacting stroke until said ram isalmost withdrawn from said receptacle in a retracting stroke.

2. A control as defined in claim 1, wherein said motor is an electricmotor with a starting winding, a motor speed responsive switchcontrolling said starting winding, a main winding, and said directionalswitch is conriected to reverse the phasing of said starting windingwith respect to said main winding, said interlock including a dooroperated switch connected in series circuit with said starting switch,said power supply, and said main winding, said bypassing means includinga normally closed bypass switch connected in parallel with said dooroperated switch and held open by said ram whenever said ram is at thetop of or withdrawn from said receptacle.

3. A control for a trash compacting machine having a receptacle, a door,a drawer unit incorporating said door and said receptacle for jointmovement between a closed compacting position and an open position, aram mounted for movement with said drawer unit in the closed position ina compacting stroke to compact material and an opposite retractingstroke to a retracted starting position, a power supply, a reversibleelectric motor connected to drive said ram, and including a motor speedresponsive switch and a starting winding, a directional switch connectedto switch the power supply to said starting winding for forward andreverse operation corresponding to the compacting and retracting strokesof said ram, a starting circuit connecting said directional switch tosaid power supply and including a starting switch,

means operated by said ram for moving said directional switch to itsforward position only when said ram is at its starting position, aninterlock switch connected between said motor and said power supply andoperative to supply power to said motor only with said drawer unit insaid closed position; the improvement comprising a switch connected tobypass said interlock switch and operated by said ram during compactingand retracting strokes to close only when at least a portion of said ramis within said receptacle.

1. A control for a compacting machine having a receptacle for trashmaterial and a door connected to said receptacle such that said door isclosed when said receptacle is in a compacting position, a ram mountedfor compacting movement in a compacting stroke entering said receptacleand an opposite retracting stroke to a retracted starting position, apower supply, a reversible motor connected to drive said ram, adirectional switch connected to control the forward and reverseoperation of said motor corresponding to the compacting and retractingstrokes of said ram, means normally holding said directional switch inits reverse position, a starting switch connected between saiddirectional switch and said power supply, and an interlock operable inresponse to opening of said door to disconnect said motor from saidpower supply; the improvement comprising means for bypassing saidinterlock once said ram has entered said receptacle in a compactingstroke until said ram is almost withdrawn from said receptacle in aretracting stroke.
 2. A control as defined in claim 1, wherein saidmotor is an electric motor with a starting winding, a motor speedresponsive switch controlling said starting winding, a main winding, andsaid directional switch is connected to reverse the phasing of saidstarting winding with respect to said main winding, said interlockincluding a door operated switch connected in series circuit with saidstarting switch, said power supply, and said main winding, saidbypassing means including a normally closed bypass switch connected inparallel with said door operated switch and held open by said ramwhenever said ram is at the top of or withdrawn from said receptacle. 3.A control for a trash compacting machine having a receptacle, a door, adrawer unit incorporating said door and said receptacle for jointmovement between a closed compacting position and an open position, aram mounted for movement with said drawer unit in the closed position ina compacting stroke to compact material and an opposite retractingstroke to a retracted starting position, a power supply, a reversibleelectric motor connected to drive said ram, and including a motor speedresponsive switch and a starting winding, a directional switch connectedto switch the power supply to said starting winding for forward andreverse operation corresponding to the compacting and retracting strokesof said ram, a starting circuit connecting said directional switch tosaid power supply and including a starting switch, means operated bysaid ram for moving said directional switch to its forward position onlywhen said ram is at its starting position, an interlock switch connectedbetween said motor and said power supply and operative to supply powerto said motor only with said drawer unit in said closed position; theimprovement comprising a switch connected to bypass said interlockswitch and operated by said ram during compacting and retracting strokesto close only when at least a portion of said ram is within saidreceptacle.